Heat-expandable microcapsules, production method therefor, and foamed molded article

Abstract

wherein the R1 moieties each independently represent a C2-12 unsaturated hydrocarbon group, the unsaturated hydrocarbon group being optionally separated by one or more of —CO—O—, —O—CO—, and —O—.

1 . A heat-expandable microcapsule having a core-shell structure including a core and a shell,
 wherein the core contains a volatile substance,   the shell contains a polymer, and   the polymer can be obtained by a reaction of a monomer mixture with an organic peroxide represented by Formula (1):   
       
         
           
           
               
               
           
         
       
       wherein in Formula (1), each of R 1  independently represents an unsaturated hydrocarbon group having 2 to 12 carbon atoms, and the unsaturated hydrocarbon group may be interrupted by any one or more of —CO—O—, —O—CO—, and —O—. 
     
     
         2 . The heat-expandable microcapsule according to  claim 1 , wherein
 R 1  in Formula (1) is any one or more of the polymerizable group represented by Formula (2) and the polymerizable group represented by Formula (3):   
       
         
           
           
               
               
           
         
       
       wherein in Formula (2), R 2  represents a hydrogen atom or a methyl group, and n represents an integer of 1 or 2; 
       
         
           
           
               
               
           
         
       
       wherein in Formula (3), R 3  represents a hydrogen atom or a methyl group, and m represents an integer of 0, 1 or 2. 
     
     
         3 . The heat-expandable microcapsule according to  claim 1 , wherein
 the monomer mixture contains a nitrile based monomer and   an amount of the nitrile based monomer in the monomer mixture is 25% by mass or more and 100% by mass or less.   
     
     
         4 . The heat-expandable microcapsule according to  claim 3 , wherein the monomer mixture further contains one type or more of the monomers selected from a group consisting of monomers having a carboxyl group, (meth)acrylamide based monomers, alkyl(meth)acrylate, ester compounds of (meth)acrylic acid and aliphatic alcohol, aryl(meth)acrylate, styrene based monomers, vinylester based monomers, and halogenated vinyl based monomers. 
     
     
         5 . A production method for the heat-expandable microcapsule according to  claim 1 , comprising at least a step of dispersing an oily mixed liquid containing the monomer mixture, the organic peroxide represented by Formula (1), and the volatile substance into an aqueous dispersion medium to obtain a dispersion; and a step of reacting the monomer mixture with the organic peroxide represented by Formula (1) in the obtained dispersion to polymerize the monomer mixture. 
     
     
         6 . A foamed molded article produced by using the heat-expandable microcapsule according to  claim 1 . 
     
     
         7 . The heat-expandable microcapsule according to  claim 2 , wherein
 the monomer mixture contains a nitrile based monomer and   an amount of the nitrile based monomer in the monomer mixture is 25% by mass or more and 100% by mass or less.   
     
     
         8 . The heat-expandable microcapsule according to  claim 7 , wherein the monomer mixture further contains one type or more of the monomers selected from a group consisting of monomers having a carboxyl group, (meth)acrylamide based monomers, alkyl(meth)acrylate, ester compounds of (meth)acrylic acid and aliphatic alcohol, aryl(meth)acrylate, styrene based monomers, vinylester based monomers, and halogenated vinyl based monomers. 
     
     
         9 . A production method for the heat-expandable microcapsule according to  claim 2 , comprising at least a step of dispersing an oily mixed liquid containing the monomer mixture, the organic peroxide represented by Formula (1), and the volatile substance into an aqueous dispersion medium to obtain a dispersion; and a step of reacting the monomer mixture with the organic peroxide represented by Formula (1) in the obtained dispersion to polymerize the monomer mixture. 
     
     
         10 . A foamed molded article produced by using the heat-expandable microcapsule according to  claim 2 .